This invention relates to a two cycle engine for a small boat and more particularly to an improved lubricating system for the two cycle engine of a small boat.
As is well known, a wide variety of watercraft are provided with internal combustion engines for powering the watercraft. In connection with the use of an internal combustion engine, it is also the practice to provide a lubricating system for the engine. With two cycle engines, although it has been the practice to mix lubricant with the fuel for the engine, there are a number of advantages to employing a separate lubricating system wherein lubricant is supplied to the engine from a separate lubricant reservoir. In many of these types of lubricating systems, the lubricant reservoir is positioned vertically above the lubricant pump when the watercraft is operating in its normal upright condition so that lubricant will be supplied to the pump under the influence of gravity. With many types of watercraft, particularly those having a highly sporting nature such as some small jet propelled watercraft that are designed to be operated by a rider wearing a swimming suit, it is anticipated that the watercraft will become inverted during its operation.
When the engine is provided with a lubricating system of the type having the lubricant reservoir positioned above the lubricant pump, the inversion of the watercraft can cause air to flow from the reservoir to the pumping system When this occurs and the watercraft is righted, if the engine is restarted immediately, the lubricant pump will pump air rather than lubricant to the engine. Obvious problems can occur when this happens.
There have been proposed lubricant pumping systems wherein the lubricant pump is provided with a self purging device that will purge air from the lubricant and return it back to the lubricant reservoir through an air return line. With such systems, inversion of the watercraft can also give rise to problems. That is, the return line can become filled with air and when the watercraft is inverted, lubricant can become forced in the line along with the air. When the watercraft is righted, the lubricant in the return line can actually force air back into the lubricant pump and the aforenoted problems will again be possible.
It is, therefore, a principal object of this invention to provide an improved lubricating system for the internal combustion engine of a small watercraft wherein it will be insured that inversion and righting of the watercraft will not cause the lubricant system to deliver air to the engine rather than lubricant.
It is a further object of this invention to provide a lubricating system for a small watercraft of the type having the lubricant reservoir above the lubricant pump and incorporating an arrangement for insuring that air cannot be delivered to the lubricant pump when the watercraft is inverted and then righted.
It is a further object of this invention to provide an arrangement for purging the air from a lubricating system of a small watercraft and wherein the air purging return line will not cause air to be forced back into the lubricant pump if the watercraft is inverted and then righted.